GENE EXPRESSION:USING DNA TO MAKE PROTEINS

PHA Biology 9

A DAY IN THE LIFE OF THE CELL

Ribosome

s

::

Blo

od

S

tr

ea

m:

:

Cytoplasm

Vesicles

(“bubbles” that

transport

proteins)

Nucleu

s

DNA

(Stores genetic information)

RNA

(Copies genetic from DNA and carries it to the Ribosome to make

proteins)

Protein could go to membrane to be released into blood stream

Golgi

Apparatu

s

(Modifies and shapes the protein)Protein

being formed

at Ribosom

e

Cell

Mem

bra

ne

(transport

s and

packages

proteins)

E.R.

Released in

to blood

stream and use

d as

hormone or o

ther

bodily st

ructu

re

ProteinRibosome

RNA

Overview: Using DNA to Make Proteins

DNA RNA Protein

Trait• Stays in the

nucleus• Copies itself

and gets passed on to new cells

• Holds instructions for making proteins

• Made in the nucleus and goes to the cytoplasm

• Uses DNA instructions to make proteins

• Used as body structures (muscle, bone, skin, hair), enzymes, transporters, hormones, etc.

• Observable characteristic• “Who you are”

[Turn your notebook sideways and write this in big letters in the middle of the page – take up the whole length of the page!

Leave plenty of space above and below it.]

Overview: Using DNA to Make Proteins

DNA RNA Protein

Trait

Transcription: The process of making RNA by copying DNA

Translation: The process of using info in RNA to make proteins

• Stays in the nucleus

• Copies itself and gets passed on to new cells

• Holds instructions for making proteins

• Made in the nucleus and goes to the cytoplasm

• Uses DNA instructions to make proteins

• Used as body structures (muscle, bone, skin, hair), enzymes, transporters, hormones, etc.

• Observable characteristic• “Who you are”

Differences between DNA and RNA

Deoxyribose sugar

Double strand (forms a helix)

Bases: A, T, G, C

Ribose sugar Single strand (can

form different shapes)

U instead of T(A, U, G, C)

DNA RNA

Objectives for Class:• Describe the major structural differences between DNA and RNA• Differentiate between structure and function differences between the types of RNA

Base Pairing between DNA and RNA

DNA RNAA ------ UT ------ AC ------ GG ------ C

Objectives for Class:• Describe the major structural differences between DNA and RNA• Differentiate between structure and function differences between the types of RNA

Transcription: Copying DNA into RNA

mRNA (the orange strand)

DNA (the red & green strands)

Objectives for Class:• Describe the major structural differences between DNA and RNA• Differentiate between structure and function differences between the types of RNA

Overview: A DNA gene is copied into RNA Occurs in the nucleus

Steps: 1. RNA Polymerase separates (unzips)

DNA strands2. RNA Polymerase makes RNA by

matching complementary nucleotides with the DNA strand

3. mRNA leaves nucleus and DNA winds back up!

Final Result: mRNA copy of a gene

mRNA

Objectives for Class:• Describe

Transcription

Objectives for Class:• Describe the purpose and major steps of transcription• Describe the purpose and major steps of translation

Three Types of RNA:

Messenger RNA (mRNA) - Carries a copy of protein-making

instructions to the ribosome Codon = 3 letters on mRNA

that stand for one amino acid Transfer RNA (tRNA) –

Carries amino acids to the ribosome Contains anticodons that match up with mRNA

codons to put amino acids in the correct order Ribosomal RNA (rRNA) –

Part of the ribosome (helps bond amino acids together)

Amino Acid attached to the top

Anti-codon on the bottom

Transfer RNA (tRNA) Structure (Draw it!)

Objectives for Class:• Describe the major structural differences between DNA and RNA• Differentiate between structure and function differences between the types of RNA

Ribosomal RNA (rRNA)

Acts like an enzyme to bond amino acids together into long chains (proteins!)

Translation Details Overview:

The gene sequence in mRNA is translated into a chain of amino acids that forms a protein

Occurs at the ribosome Steps:

1. mRNA enters the ribosome2. tRNA molecules bring amino acids to the

ribosome 3. tRNA anticodons match with mRNA

codons to put amino acids in the right order According to the Genetic Code

4. Ribosome connects the amino acids into a long chain

Final Result: A polypeptide (protein)

t RNA

mRNA

t RNA

Ribosom

e

Making Proteins at the Ribosome

Objectives for Class:• Describe

Growing

Protein

Anticodon

Codon

Amino Acid

Objectives for Class:• Describe the purpose and major steps of transcription• Describe the purpose and major steps of translation

Translation

Objectives for Class:• DescribeObjectives for Class:• Describe the purpose and major steps of transcription• Describe the purpose and major steps of translation

mRNA strand

Growing protein chain

Ribosome

Transcription & Translation

Objectives for Class:• Describe

Transcription

Translation

Reading The Genetic Code The letters in the wheel

are mRNA codons

Start in the middle! This is the first letter in

the codon

Move to the middle ring (2nd letter in the codon)

Then go to the outer ring of letters (3rd letter in the codon)

Outermost ring = amino acids!

Reading The Genetic Code: ExamplesFollow along with the

examples on your worksheet!

Example 1: CAG

1st base = C 2nd base = A 3rd base = G

Therefore theamino acid is…

Glutamine!

Example 2: GUU Valine

Reading The Genetic Code: Longer Example

Example 3: GCCAGCUAG

Step 1: Break it into 3-letter sections (codons)

GCC AGC UAG

Step 2: Decode each codon

GCC = Alanine

AGC = Serine UAG = STOP

(end of protein sequence)

1

2

3

Gene Mutations Activity: Part I Review

What is a Genetic Mutation? A change in the base-pair sequence of DNA

The three types of point mutations: substitution (switch one DNA nucleotide

for another) insertion (add an extra nucleotide into the

DNA sequence) deletion (leave out one nucleotide in the

DNA sequence)

Objectives for Class:• Describe the major differences between substitution and frame-shift mutations

Genetic Mutations Activity – Substitution Mutations

Original DNA Sequence

Substitution

Substitution/ Silent Mutation

Changes the Amino Acid

Does not Change the Amino AcidObjectives for Class:• Describe the major differences between substitution and frame-shift mutations

Genetic Mutations Activity –Frame-Shift Mutations

Frame-Shift Mutations Original DNA Sequence

Frame-Shift: Deletion of nucleotide

Frame-Shift: Insertion/ Addition of nucleotide

Changes all Amino Acid after mutation

Changes all Amino Acid after mutation

Objectives for Class:• Describe the major differences between substitution and frame-shift mutations

Lab: Sickle Cell and Genetic Mutations

Background Information BrainstormInfo on Sickle Cell AnemiaNormal vs. Sickled Cells (shape is different)Genetic disease (get it from parents’ genes)Two copies of gene = sickle cell anemiaOne copy of gene = “carrier” for sickle cell anemia – protected from malariaMalaria – disease caused by mosquitoes that live in tropical places (ex: sub-Saharan Africa)People of African descent are more likely to carry the sickle cell gene b/c it protected their ancestors from malaria

Symptoms of SCA: tired easily, lots of muscle pain b/c blood cells stick together and block blood flow.

What anemia isHow SCA came to be.

Lab: Sickle Cell and Genetic Mutations

Background Information BrainstormInfo on Genes and Mutations:What a gene isWhat a mutation isDifferent types of mutations (substitution and frame-shift (deletion and insertion))DNA RNA protein trait and how a mutation would affect this.Transcription and translation.

Valine:

Glutamic acid: